The Blinx games aren't bad, so I'm not sure why it failed other than being a bit too little, too late. The era of platform games was starting to fade out at that point, in large thanks to games like Halo.
I haven't seen many people say that the blinx games are good, even OG xbox fans usually talking about other games pretty much never blinx and those games are fairly common so rarity can't be an excuse.
I think it's just a mediocre platformer,
Check all other platformers, mario, sonic, crash bandicoot all of those where some of the best games or at least very excellent games on the system period. I'm not to sure if you could say the same thing for blinx.
That's probably where it failed. it isn't good enough for a main mascot game reason why they never went through with it if I had to guess.
The term budget mascot would definitely apply in the case of blinx if the games actually where the main mascot games for xbox or at the very least in the kids department, since even it did happen, master chief would still be the mascot for the more mature audience of xbox.